I use CS5. All of a sudden I can't open psd files. They all look like the image below with this almost checkboard like appearance on them. jpgs open fine. This is happening with files on multiple EHDs so it doesn't seem to be an issue with one file or set of files. If anyone knows what night be causing this or how to fix it, I'd be most grateful. I tried reinstalling CS5 but the problem remained. Thanks in advance.
Does turning off OpenGL in the Performance Preferences and restarting Photoshop have any bearing on the issue?
Clearly it's a display problem as the Layers panel thumbnail is okay.
Christoph is exactly on point, the display driver is faulty. Perhaps you got a new one via Windows Update. The drivers that come through Microsoft that way often cause problems.
Go to the web site of the maker of your video card and download and install their latest version for your hardware and OS. Make sure to carefully follow their instructions, as the installers for drivers are particularly tricky.